1. Field
This apparatus relates to position correction when a magnetic tape is accommodated in a cell of a magnetic tape library apparatus.
2. Description of the Related Art
The capacity of hard disks is increasing markedly. If data is lost, the loss is not just a problem for an individual or a company it may affect a large number of people. Storing a backup of data is extremely important for the use of a computer in case of the loss of data. To store a backup of data, a magnetic tape library apparatus is frequently used. The apparatus uses a magnetic tape as a storage medium. A magnetic tape library apparatus accommodates several to several hundred magnetic tapes. The apparatus has at least one drive, and one or two robots. The apparatus also has a casing called a locker with cells attached for accommodating the magnetic tapes. The apparatus operates a robot to insert the magnetic tape to the cell, or extract the magnetic tape from the cell, carry the magnetic tape, and mount the magnetic tape on the drive for read or write operation. When the read or write operation is completed, the robot demounts the magnetic tape from the drive, carries the magnetic tape, and inserts the magnetic tape to the former cell.
FIGS. 1A and 1B are explanatory illustrations showing cells of a related art.
FIG. 1A shows an example of a normal position. Cells 5 are arrayed in a matrix. Relative flags 61 are arranged at three positions of the matrix. A locker may be deformed due to variation in assembly, transport, installation environment, and the like. As the locker is deformed, the cells may be deformed accordingly. FIG. 1B shows an example with deformation. The deformation usually appears in the form of a parallelogram because of the structure of the locker, and sometimes includes a rotation. Thus, the center positions (x1, y1), (x2, y2), (x3, y3) of the relative flags 61 in the normal positions are shifted to (x′1, y′1), (x′2, y′2), (x′3, y′3). To correct the deformation, relative flags 61 located on a deformed surface may be measured, and distances from default positions of the relative flags 61 to shifted positions thereof may be calculated. The distances of the relative flags 61 are measured with, for example, a charge-coupled device (CCD) sensor mounted on a robot. The position of the robot is corrected, so that the robot is controlled to reliably hold the magnetic tape. With the above-described controlling method, the relative flags 61 have to be provided for the correction of relative values, this may reduce the number of magnetic tapes in the magnetic tape library apparatus.